A wide variety of information can be represented in a hierarchical structure. One format used for representing information in a hierarchical structure is extensible markup language (XML) format. An XML document includes an arrangement of one or more nodes containing information and parent-child relationships among the nodes.
It may be desired under a variety of circumstances to encrypt hierarchically structured information in order to prevent unauthorized access. For example, an entire XML document can be encrypted using an encryption key. Information contained in the document can be accessed by decrypting the document using an appropriate decryption key.
In certain circumstances, it may be desired to encrypt less than an entire XML document. One technique for XML document encryption is described in International Publication No. WO 02/46893, entitled, “A method and apparatus for providing XML document encryption.” Another technique is described in “XML Encryption Syntax and Processing,” by W3C.
Despite these techniques, there exists a need for an improved technique for encrypting hierarchical structured information, and particularly, for encrypting XML documents. It is toward this end that the present invention is directed.